The background of the invention will be discussed in two parts.
1. Field of the Invention
This invention relates to mating and de-mating of electrical connector sub-assemblies having multiple electrical connections that employ a jackscrew to bring the sub-assemblies together in mutual alignment, and more particularly to a two-part jackscrew system for preventing undesired mating and de-mating problems during mating and de-mating of miniature electrical sub-assemblies. Employed is a captive retainer, or thrust ring crimped around the jackscrew shaft that acts to restrict the thrust ring from opening under mounting and de-mounting load forces.
2. Description of the Related Art
Electrical connector assemblies in which multiple electrical connections are to mate simultaneously commonly consist of two sub-assembly connectors, one generally having an array of male contacts, and another having a corresponding, or complimentary, array of matching receptive female contacts. A pair of jackscrew couplings is commonly used for aligning and capturing the sub-assemblies to effect proper alignment and reliable electrical contact between the two sub-assemblies.
Although there have been improvements in related art jackscrew systems, most typically include E-rings for capturing the screw. However, E-rings are prone to dislodge under thrust or screw rotation conditions during mating and de-mating of the assemblies, such dislodgment of the E-ring often accompanied by displacement, or fall-out, of the screw thereby creating serious problems. For instance, E-ring dislodgment often causes electrical shorts in surrounding electrical circuits. Further, the E-ring is substantially larger than the jackscrew shaft in order to provide three-point leveraged locking force with the shaft. During mating and de-mating procedures the E-ring must rotate freely with the shaft and if either ear of the E-ring should encounter an obstacle during such rotation the E-ring, will unlock from the shaft and fall off, thus freeing the jackscrew from the connector body.
This has been a problem, especially with miniature connectors, as it is difficult for the E-ring to rotate with the shaft without hitting some part of the plug and thus being forced off the shaft. To enlarge the connector bodies to accept the E-ring would be contra-productive for miniaturization of the connectors. A known apparatus for mating an electrical plug and receptacle having a jackscrew E-ring in accordance with the prior art is disclosed in U.S. Pat. No. 4,865,560 issued to Thomas on Sep. 12, 1989, which patent is incorporated by reference herein.
Other jackscrews and jackscrew couplings, exemplary of the related art for mating and de-mating electrical assemblies having multiple electrical connectors, are shown and described variously in U.S. Pat. No. 5,391,091 issued to Nations on Feb. 21, 1995, U.S. Pat. No. 5,628,653 issued to Haas et al. on May 13, 1997, U.S. Pat. No. 5,766,035 issued to Alibert on Jun. 16, 1998, and U.S. Pat. No. 6,056,581 issued to Rothenberger on May 2, 2000.
However, in light of prior art problems, what is needed is improved jackscrew means for mounting and de-mounting electrical sub-assemblies that provides mechanical and electrical reliability, uses a minimum number of parts, is inexpensive to produce, and can be quickly assembled and replaced with assured quality and reliability. It is thus an object of the present invention to provide an improved two-part jackscrew system that instead of an E-ring, employs.a captive retainer, or thrust ring, crimped around the jackscrew shaft that acts to restrict the thrust ring from opening under mounting and de-mounting load forces. The present invention has particular application to miniature electrical assemblies having multiple electrical connectors.
The present invention is directed toward providing an improved jackscrew system preventing undesired problems encountered in mating and de-mating of electrical sub-assemblies having multiple electrical connectors, and especially of miniature electrical sub-assemblies.
This improvement is accomplished by providing a two-part jackscrew system that captivates the screw during mating and de-mating of the electrical connectors thus preventing problems arising from dislodgment of the screw. The system utilizes a thrust shoulder addition to the jackscrew that separates the jackscrew threads from a non-threaded portion of the screw shaft, and a retaining or crimp, ring. The retaining ring is generally C-shaped in the form of an annular ring, or washer, with an annular portion removed. The ring is crimped, or closed, about the non-threaded portion of the jackscrew shaft and positioned substantially against the thrust shoulder. The ring is fabricated of spring material and has a thickness approximately one-third of the inner diameter of the ring. The ring edges are substantially free of burrs and have corner radii of about 0.001 inches.
A counter-bore is provided in the connector, or plug, body that accepts the jackscrew. The crimp ring enters the counter-bore when under the load of de-mating this connector, or plug, body from the mated, or receptacle, connector body. The counter-bore acts to restrict the crimp ring from opening under de-mate forces when the thrust shoulder applies such forces against the crimp ring and thereby against the plug body, and thus assures retention of the crimp ring under operating conditions.
Thus, in operation as described, for each of the jackscrews the interrelated action of the jackscrew, jackscrew shoulder, retaining ring, and the body surface of the counter-bored recess collectively serve to capture the jackscrew to prevent the usual de-mounting problems associated with mating and de-mating electrical sub-assemblies.
The plug body counter-bore further serves to provide an axial tolerance to assure sufficient jackscrew thread engagement with the receptacle body. Additionally, the crimp ring, when crimped around the jackscrew shaft, creates thrust interaction with the screw shoulder to allow for self-centering of the screw when engaged with the receiving threads of the receptacle body.